Rheometers are instruments for determining the flow behaviour for example of viscoelastic samples. Known methods for determining the flow behaviour are, for example, rotation tests, creep tests, relaxation tests, and oscillation tests. By means of a rheometer it is possible, for example, to investigate the flow behaviour of fluids and supercooled liquids and also the deformation behaviour of solid bodies.
AT 508 706 B1 relates, in particular, to a method for investigating samples with the use of a rheometer. The rheometer comprises a measuring shaft that is driven by a motor and that carries a first measuring part. Furthermore, the rheometer comprises a measuring gap for the sample, which measuring gap is delimited by the first measuring part and a further measuring part, and comprises a moment detector for detecting the torsional moment of the motor, and a measuring unit for determining the normal force exerted by the sample on the measuring shaft or on the first measuring part. A further measuring shaft, or the axis of rotation of a further measuring shaft, is supported so as to be aligned with the measuring shaft or on the axis of rotation of the measuring shaft, which further measuring shaft is driven by a dedicated further motor and can be affixable or is affixed to the further measuring part. In order to determine the torsional moment exerted by the further motor, a further moment detector is provided. Furthermore, for determining the normal force exerted by the sample on the further measuring part or on the further measuring shaft a further measuring unit is provided.
U.S. Pat. No. 6,691,569 B1 discloses an extensional rheometer, comprising a rotatable primary winding drum and one or more secondary rotatable winding drums. One sample is affixed to the primary winding drum and to each secondary winding drum. Counter rotation of the primary winding drum and each secondary winding drum causes each affixed sample to stretch until rupture. The load response to each primary and secondary winding drum set caused by stretching the sample is measured with a load-sensing device. An environmental control may be provided for testing of samples under various conditions.
US 2012/0234081 A1 discloses an apparatus or a rheometer for determining the extensional properties of a material comprising a first end and a second end. The rheometer comprises first and second rollers gripping the first end of the material. Third and fourth rollers grip the second end of the material. An input shaft rotates the first, second, third and fourth rollers to pull the first and second ends of the material in opposite directions in order to stretch the material.
DE 11 2005 001 096 T5 relates to a system for measuring the extensional characteristics of a sample by means of a stationary cylinder and a movable cylinder, wherein the sample is affixed to the movable cylinder and to the stationary cylinder in such a manner that part of the sample, which part touches neither the movable cylinder nor the stationary cylinder, extends from a tangent of the movable cylinder to a tangent of the stationary cylinder, wherein the movable cylinder is rotated about an axis of the stationary cylinder by rotating a motor drive shaft. Thereby the movable cylinder is rotated about an axis of the movable cylinder, wherein a resistance is generated by the sample when the sample is extended between the movable cylinder and the stationary cylinder as a result of rotation of the movable cylinder about the axis of the stationary cylinder and rotation of the movable cylinder about the axis of the movable cylinder, wherein a torsional moment, acting on the movable cylinder and generated by the resistance, is measured.